It has been reported in recent years that a ligand of GPR40, which is one of the G Protein-Coupled Receptors (GPCR), is fatty acid and GPR40 in pancreatic β cell is deeply involved in insulin secretion action (Nature, 2003, vol. 422, pages 173-176). Thus, a GPR40 agonist promotes insulin secretion, a GPR40 antagonist inhibits insulin secretion, and the agonist and the antagonist are useful as a therapeutic agent for type 2 diabetes, obesity, impaired glucose tolerance, insulin resistance, neurodegenerative diseases (Alzheimer's disease) and the like (see WO03/068959 and WO02/057783).
In contrast, there are many carboxylic acid compounds reported to be useful as therapeutic agents for various disease.
For example, WO2004/041266 discloses that a compound having an aromatic ring and a group capable of releasing cation is useful as a GPR40 receptor function regulator.
WO03/074050 discloses that a compound represented by formula:
wherein    W is O, S, CR5R6, (CH2)p-cycloalkylene or (CH2)p-heterocycloalkylene wherein p is 0 to 2;.    X0 and X1 are each 0 or S;    Ar1 is an optionally substituted aryl or an optionally substituted heteroaryl;    R1, R2, R3 and R4 are each an hydrogen atom and the like; and    n is 0 to 5,    is useful as a PPAR activity regulating agent.
U.S. Pat. No. 6,242,493 discloses that a compound represented by formula:
wherein    HET is a 5- to 12-membered monocyclic or bicyclic aromatic ring system;    A is W, CO, C(R7)2—W wherein W is O, S(O)n and the like, and the like;    R1, R2 and R3 are each a hydrogen atom, a halogen, a lower alkenyl-HET(Ra)4-9 and the like;    X is an optionally substituted 5- to 10-membered monocyclic or bicyclic aryl or an optionally substituted heteroaryl, and A and B are bonded to the aryl or heteroaryl both at the ortho positions;    Y is O, S(O)n, NR17, a bond or —CR18═CR18;    B is —(C(R18)2)p—Y—(C(R18)2)q— wherein p and q are each 0 to 3, and when Y is O, S(O)n, NR17, a bond or —CR18═CR18, then p+q should be 0 to 6, and when Y is a bond, then p+q should be 1 to 6; and    Z is OH or NHSO2R19 wherein R19 is a lower alkyl, a lower alkenyl and the like,    is a prostaglandin receptor ligand, and useful for the treatment of pain and the like.
WO2005/019151 discloses that a compound represented by formula:
wherein    A1 is a bond, CH2, O or S, and when A1 is CH2, then A1 optionally forms a 3- to 6-membered carbon ring together with R4 or R5;    A2 and A3 are each O or S;    E1, E2, E3, E4 and E5 are each CH or carbon substituted by A2 or R3, and at least one of them is nitrogen;    Q is C(O)OR6 wherein R6 is a hydrogen atom or a C1-6 alkyl, and the like;    Y is a bond, a C1-6 alkyl or a C3-6 cycloalkyl;    Z is aryl, 5- to 10-membered heteroaryl and the like;    r is 1 to 4;    R1 and R2 are each a hydrogen atom, a C1-6 alkyl and the like;    R3 is a hydrogen atom and the like; and    R4 and R5 are each a hydrogen atom or a C1-6 alkyl, is a PPAR agonist.
WO02/053547 discloses that a compound represented by formula:
wherein    R1 is an optionally substituted 5-membered aromatic heterocyclic group;    X is a bond and the like;    Q is a C1-20 divalent hydrocarbon group;    Y is a bond and the like;    ring A is an optionally substituted aromatic ring;    Z is —(CH2)n-Z1— or —Z1—(CH2)n- wherein n is 1 to 8, Z1 is O and the like;    ring B is an optionally substituted pyridine, an optionally substituted benzene or an optionally substituted naphthalene;    U is a bond and the like;    W is a C1-20 divalent hydrocarbon group; and    R3 is a hydroxyl and the like,    is a PPAR ligand, and useful for the prophylaxis or treatment of diabetes and the like.
WO02/076959 discloses that a compound represented by formula:
wherein    R1 is an optionally substituted 5-membered heterocyclic group;    X and Y are each a bond, O, S and the like;    Q is a divalent C1-20 hydrocarbon group;    ring A is an aromatic ring optionally further having 1 to 3 substituents;    Z is —(CH2)n—Z1— or —Z1—(CH2)n— wherein n is 1-8; and Z1 is O and the like;    ring B is a 5-membered heterocycle optionally further having 1 to 3 substituents;    W is a divalent C1-20 saturated hydrocarbon group; and    R2 is —OR8 wherein R8 is a hydrogen atom or an optionally substituted hydrocarbon group, and the like,    is a PPAR ligand, and useful for the prophylaxis or treatment of diabetes and the like.
However, none of the above-mentioned prior art reports on the compound of the present invention.